The interesting whisker/barrel system

Introduction In the late 20th century, Woolsey and Van der Loos discovered a specific projection map in the rodent somatosensory cortex corresponding to the contralateral face whiskers, designated barrel. Because rodents are nocturnal animals, their whiskers serve to recognize the external world, similar to our eyes and fingers. Each barrel is associated with an individual whisker on the snout, and ambient information received by the whiskers is conveyed to the somatosensory cortex via the trigeminal ganglia, trigeminal nuclei, and thalami. Because the brain maps for whiskers also exist above the brainstem, it suggested that one-barrel processes sensory information for one facial whisker. This one-to-one relationship, thought to be important in transmitting information correctly. Moreover, if sensory input is blocked from early development, the whisker-matched brain map will be unable to form, or the formed map will disappear. As such, the whisker/barrel system is refined during postnatal periods by neural activity elicited by stimuli to vibrissae. Studying the whisker/barrel system is advantageous, as it can be easily probed, with both anatomical and functional techniques, and for nearly half a century, many anatomists and electrophysiologists have elucidated the mechanisms in the whisker/barrel system, such as activity-dependent synaptogenesis of barrel cortex. This review outlines the detailed pathway, history, mechanism of development, as well as recent evidence of the whisker/barrel system from an anatomical perspective and is meant to spur the interest of young neuroanatomists in this elegant neural circuit. Conclusion Given the simple sensory pathway amenable to interrogation, the whisker/barrel system of rodents attracts researchers’ attention as an important model for understanding basic principles of cerebral cortical development in mammals. Moreover, the visualisation of brain map facilitates further study of the whisker/barrel system. Therefore, we encourage investigators interested in the role of sensory experience on neuronal networks to study the whisker/barrel system.